Heavy machines including, for example, dozers, loaders, excavators, motor graders, etc. typically comprise a number of hydraulic actuators to perform various functions. Actuators are fluidly connected to a pump on the machine that provides pressurized hydraulic fluid to chambers within the actuators. As the pressurized hydraulic fluid moves into or through the chambers, the pressure of the fluid acts on hydraulic surfaces of the chambers to affect movement of the actuator and a connected implement (i.e., work tool). When the pressurized fluid is drained from the chambers it is returned to a low pressure tank on the machine.
For machinery that includes a hydraulic system, it is typical practice to warm the fluid prior to valve and/or pump calibration. Also, when operating in particularly cold environments, it is often desirable or necessary to warm up the hydraulic fluid in order to improve hydraulic system performance.
In a commonly implemented hydraulic system, a single load sensing pump (or fixed displacement pump in an open center valve configuration) is utilized to provide hydraulic flow to all implemented functions on the unit. In such a system, stalling one function raises the system pressure to its relief setting. Actuating a second function causes the pump to move fluid at that relief pressure setting, thus consuming hydraulic power and heating the fluid.
In a dual pump system, pump flow may be split such that each pump independently controls an implement function. Stalling one function while actuating another does not necessarily lead to high pressure and high flow at each pump. Accordingly, for example, a first hydraulic pump may be stalled at high pressure with no flow while a second pump may move fluid at a low pressure. Neither the first pump nor the second pump consumes the power necessary for rapidly warming the hydraulic fluid.
This issue causing a lack of warming in a dual pump configuration is also applicable to other hydraulic system configurations. A single function system, for example, being controlled by a single pump may experience this issue due to not having the capability of both stalling over relief and actuating simultaneously.